The present disclosure relates to sheet post-processing devices and image forming apparatuses.
More and more recent image forming apparatuses such as copiers and multifunction peripherals are equipped with a sheet post-processing device, such as a finisher, for performing post-processing of sheets, such as stapling of sheets. A sheet post-processing device sequentially receives sheets having been printed by the main body of an image forming apparatus. To staple printed sheets, a conveyance section of the sheet post-processing device conveys the printed sheets to a processing tray provided within the sheet post-processing device. After conveying the sheets to the processing tray, the sheet post-processing device moves the sheets using a paddle along the processing tray toward a regulating member that is mounted on one end of the processing tray. In the manner described above, the sheets stacked on the processing tray are aligned at the edges thereof. The sheet post-processing device then staples the thus aligned sheets.
Until the sheets on the processing tray are stapled and conveyed to the exit port, subsequent sheets to be stapled cannot be conveyed to the processing tray. The sheet post-processing device is therefore provided with an evacuating member. During the time until the stapled sheets are conveyed from the processing tray to the exit port, the evacuating member evacuates, from the conveyance section, sheets sequentially fed from the image forming apparatus. The sheets evacuated by the evacuating member are stacked into a pile and held in standby. The pile of evacuated sheets is conveyed through the conveyance section onto the processing tray after the stapled sheets are conveyed from the processing tray to the exit port.
However, when three sheets are stacked into a pile, moving the pile toward the regulating member using a paddle may fail to ensure that the edges of the uppermost, lowermost, and intermediate sheets reach the regulating member. Thus, the edges of the three sheets may remain unaligned. One solution disclosed to address the problem noted above involves stacking three sheets into a pile such that, in a state where the pile is conveyed onto the processing tray and not yet moved toward the regulating member, the edge of each sheet protrudes toward the regulating member beyond the edge of an immediately lower sheet.